A kind of fusion spectrum picture and laser radar data carry out city density method of estimation
Technical field
The invention belongs to digital image processing field, belong to digital image processing field, particularly relate to a kind of fusion spectrum
Image and laser radar data carry out city density method of estimation.
Background technology
Many/high spectrum image (multispectral or high spectrum image) is provided that the spectrum and spatial information, laser that target is abundant
Radar is provided that the accurate elevation information of target.Many/high spectrum image and laser are provided from the information viewpoint provided
Radar data has message complementary sense advantage.Both data sources of associating have obtained extensively in fields such as agricultural, forestry, urban development plannings
General application.
City, as the product of human development, along with the increase of population, scientific and technological progress, is constantly expanding.Occupation of land face, city
Long-pending increase, it is meant that the minimizing of cultivated area.Countries in the world use city vertical direction development tactics to alleviate this one after another
Contradiction, therefore regardless of the commercial center in city, or residential block all occurs in that a large amount of high buildings and large mansions.Make just with tradition
Space two-dimensional urban development density index city density is evaluated not rationally, it is necessary to consider the height of city vertical direction
Degree information.This has promoted to combine the spectrum utilizing many/high spectrum image to provide and space two-dimensional information and laser radar data carries
The vertical direction elevation information of confession carries out city density estimation.
In order to calculate city density index, it is necessary to first obtain atural object and cover thematic map.If three-dimensional (3-D) index is also
Must be known by the elevation information of correspondence.Can be a pixel, a net for calculating the area-of-interest of city density index
Lattice, the circle specifying radius or other self-defined shape.If using single pixel as area-of-interest, then can only calculate
Two dimension (2-D) city density index, mixes technology by spectrum solution and calculates the ratio shared by specific atural object in sub-pixel level.With
When other area-of-interest calculates object as index, researchers propose many 2-D indexs to evaluate city density: if not
Water impermeable surface area, building coverage rate, vegetation coverage etc.;Relative to 2-D index, 3-D index is little, as vegetation volume,
Building volume.
The problem that 2-D index is single, 3-D index is few of utilization is there is at present, it is impossible to close in city density estimates application
Reason, thoroughly evaluating city density.For this problem existed, the present invention combines the many/high spectrum image of utilization and laser radar
Data calculate can the 3-D index of rational evaluation city density, and combine 2-D and 3-D index city density more rationally commented
Valency.
Summary of the invention
The present invention solves in existing city density method of estimation, the 2-D index that there is utilization is single, 3-D index is few, nothing
Method rationally, the problem of thoroughly evaluating city density, and propose a kind of merge spectrum picture and laser radar data to carry out city close
Degree method of estimation.
A kind of fusion spectrum picture and laser radar data carry out city density method of estimation, sequentially include the following steps:
One, obtain many/high spectrum image and laser radar data, respectively two kinds of data sources are carried out pretreatment, utilize and swash
Optical radar data genaration digital surface model (DSM), and in two kinds of data sources, select control point, above two data source is entered
Row registration;
Wherein, spectrum picture pretreatment is corrected and Geometry rectification for radiation;It is unusual to laser radar data pretreatment
Point is rejected and image tiles;
Two, on many/high spectrum image, extract spectral information and spatial information, laser radar data extracts height letter
Breath:
Wherein spectral information includes original spectrum wave band, normalized differential vegetation index and normalization building index, spatial information
Including the space characteristics by using average, variance, morphology and Gabor spatial filter to generate;On laser radar data
Extracting elevation information is normalization digital surface model;
Three, the spectral information, spatial information and the elevation information that extraction are obtained are input in grader, obtain classification scheme
Figure;
Four, combine the elevation information utilizing classification scheme figure and laser radar to provide and carry out city density index calculating,
Become city density thematic map throughout one's life;
Wherein city density index includes that 2-D and 3-D index, 2-D index are vegetation coverage and artificial surfaces coverage rate;
3-D index is building floor space and the ratio of usable floor area and building collection exponentially.
The present invention includes following beneficial effect:
1, due to the elevation information that make use of laser radar data to provide, 3-D index that can be reasonable in design, the mesh overcome
The problem that the 3-D index of front existence lacks;
2, carrying out city density when evaluating, the present invention combines that to make use of 2-D and 3-D index to carry out city density more reasonable
Evaluate, overcome tradition and use single index to be evaluated the unreasonable problem existed.
Accompanying drawing explanation
Fig. 1 is the method for the invention schematic flow sheet.
Detailed description of the invention
Understandable for enabling the above-mentioned purpose of the present invention, feature and advantage to become apparent from, below in conjunction with Fig. 1 and being embodied as
The present invention is further detailed explanation for mode.
A kind of fusion spectrum picture and laser radar data described in detailed description of the invention one, present embodiment carry out city
Density estimation method, sequentially includes the following steps:
One, obtain many/high spectrum image and laser radar data, respectively two kinds of data sources are carried out pretreatment, utilize and swash
Optical radar data genaration digital surface model (DSM), and in two kinds of data sources, select control point, above two data source is entered
Row registration;
Wherein, spectrum picture pretreatment is corrected and Geometry rectification for radiation;It is unusual to laser radar data pretreatment
Point is rejected and image tiles;
Two, on many/high spectrum image, extract spectral information and spatial information, laser radar data extracts height letter
Breath:
Wherein spectral information includes original spectrum wave band, normalized differential vegetation index and normalization building index, spatial information
Including the space characteristics by using average, variance, morphology and Gabor spatial filter to generate;On laser radar data
Extracting elevation information is normalization digital surface model;
Three, the spectral information, spatial information and the elevation information that extraction are obtained are input in grader, obtain classification scheme
Figure;
Four, combine the elevation information utilizing classification scheme figure and laser radar to provide and carry out city density index calculating,
Become city density thematic map throughout one's life;
Wherein city density index includes that 2-D and 3-D index, 2-D index are vegetation coverage and artificial surfaces coverage rate;
3-D index is building floor space and the ratio of usable floor area and building collection exponentially.
Present embodiment includes following beneficial effect:
1, due to the elevation information that make use of laser radar data to provide, 3-D index that can be reasonable in design, the mesh overcome
The problem that the 3-D index of front existence lacks;
2, carrying out city density when evaluating, present embodiment is combined and be make use of 2-D and 3-D index to carry out city density more
Rational evaluation, overcomes tradition and uses single index to be evaluated the unreasonable problem existed.
Detailed description of the invention two, present embodiment are to a kind of fusion spectrum picture described in detailed description of the invention one and to swash
Optical radar data carry out further illustrating of city density method of estimation, and the control point described in step one is road junction,
Or the flex point of building.
Detailed description of the invention three, present embodiment are to a kind of fusion spectrum picture described in detailed description of the invention one or two
Carrying out further illustrating of city density method of estimation with laser radar data, the laser radar data described in step one is unusual
Point refers to that height that the objects such as the bird due to airflight, floating rubbish and kite cause, apparently higher than the some cloud of atural object, is adopted
Carry out the unusual cloud data of laser radar by statistics with histogram method to reject.
Detailed description of the invention four, present embodiment are to a kind of fusion spectrum one of detailed description of the invention one to three Suo Shu
Image and laser radar data carry out further illustrating of city density method of estimation, the normalization numeral table described in step 2
Surface model calculates as follows:
1, lidar image filtering based on mobile Quadratic Surface Fitting, is divided into the point set in digital surface model
Ground point and non-ground points two parts, being embodied as step is:
A, choosing suitable filter window size m × n, wherein the size of m and n is 102The rice order of magnitude;
B, in this window, choose minimum 10 point, as initial seed point, be input in the point set P of ground, this
10 points must be the point that on ground, object is constituted;
C, utilizing the point in point set P to carry out at Quadratic Surface Fitting, the functional equation involved by matching is:
Wherein, (xi,yi) it is i-th point coordinate in the picture, ZiFor the height value that this point is corresponding;
Point input in being gathered by P successively, obtains a series of equation group, solves each coefficient under criterion of least squares
c0,c1,...,c5, so that it is determined that surface equation;
Other height put are predicted by the surface equation that d, utilization obtain, if the difference of predictive value and actual value is more than threshold
Value T, then judge that this point is as non-ground points;Otherwise, then this point is ground point, then joins in the point set P of ground by this point, again
Calculate each coefficient, obtain new curved surface, be so repeated up to the most all judge complete;
E, moving window, to other position of image, complete the filtering of entire image;
2, the generation of normalization digital surface model:
The algorithm using inverse distance weighted interpolation carries out height interpolation, during interpolation gives the ground point near away from interpolation point
Bigger weights, first centered by interpolated point, determine proper number N0Nearest neighbor point as source sampling point, it is assumed that interpolated point
For S0(x0,y0), sampled point is Qi(xi,yi,zi), i=(1,2 ..., N0), the mathematic(al) representation of inverse distance-weighting average interpolation
As follows:
WhereinHeight Estimation value for interpolated point;λiWeights for ith sample point;ZiHeight for ith sample point
Angle value, λiAnd ZiTried to achieve by below equation:
diDistance for ith sample point to interpolated point:
Wherein p is positive integer, and when p value is 2, the effect of interpolation is best;
After completing Interpolation Process, i.e. generating digital terrain model (DTM), then subtracting each other with DSM Yu DTM is exactly normalization number
Word table surface model.
Detailed description of the invention five, present embodiment are to a kind of fusion spectrum one of detailed description of the invention one to four Suo Shu
Image and laser radar data carry out further illustrating of city density method of estimation, and the grader described in step 3 is decision-making
Tree, support vector machine or neutral net.
Detailed description of the invention six, present embodiment are to a kind of fusion spectrum one of detailed description of the invention one to five Suo Shu
Image and laser radar data carry out further illustrating of city density method of estimation, and the vegetation coverage described in step 4 is pressed
Equation below calculates:
Wherein, VF is vegetation coverage, AtFor the region area covered by trees in area-of-interest, AgFor region of interest
The region area covered by grass and shrub in territory, AAOIArea for area-of-interest;
Described artificial surfaces coverage rate calculates as follows:
Wherein, ASC is artificial surfaces coverage rate, AbFor the region area covered by building in area-of-interest, AiFor sense
By the artificial earth's surface such as road, square occupied area in interest region;
Described building floor space is calculated as follows with the ratio of usable floor area:
Wherein, AabFor building floor space, AflFor building usable floor area, it is assumed here that every floor is high 3 meters, floor
Number N is pressed formula and is calculated:Calculate, wherein HBRefer to that building is high,Represent and round downwards;Building usable floor area presses formula
Calculate:WhereinArea for every floor;
Described building collection exponentially is calculated as follows:
Wherein, DbFor the distance between two solitary building centers every in area-of-interest, Median represents and takes intermediate value, NbFor
Building number in area-of-interest.
Detailed description of the invention seven, present embodiment are to a kind of fusion spectrum one of detailed description of the invention one to six Suo Shu
Image and laser radar data carry out further illustrating of city density method of estimation, generate city density master described in step 4
The particular content of topic figure is: each pixel is calculating center, 250 meters be the border circular areas of radius be the sense of corresponding center pixel
Interest region carries out city density (UD) and estimates, calculates as follows:
UD=(BA+ASC)-(VF+iFAR)
Wherein, by vegetation coverage, artificial surfaces coverage rate, the ratio of building floor space and usable floor area and building
Collection exponentially substitutes into before city density estimation formulas calculates and is all normalized to 0 to 1, and the UD value finally given is interval is [-2,2],
Value is the biggest, and to represent city density the biggest.